I want to create a checkbox type spreadsheet that will autofill line data to
a total sheet. What do I use? Formulas? Which one, and how?

ExCell H63 will be filled in with the amount in F55 if I check G55. Then
check a secondary, (G45), and H64 will will autofill with F45
F G
45 103 (X) checked second
55 87 (X) checked first
72 19 (X) checked last

AKA...Applicant 87 (H63) first to populate
Spouse 103 (H64) Second
Child 19 (H65) next and so on